1. Field of the Invention
The present invention relates to a bolt-anchor, or insert, adapted to be embedded in concrete; and more particularly to an insert having a slightly compressible extension, or mounting prong, connected to one end thereof by an annular frangible portion.
2. The Prior Art
Numerous types of inserts have been heretofore devised for embedment in concrete, but many of these have the disadvantage that they require the use of nails, bolts or other fasteners to retain the insert in place during pouring of the concrete. Many of such inserts also require the use of tools to remove the fasteners to free the mold from the concrete casting.
One prior form of insert requires the cooperation of two workmen to mount the same on the wall of a large mold, one workman being required to hold the insert in place on one side of the mold, while the other workman, on the opposite side of the mold, is tightening a bolt to secure the insert in place. Moreover, such insert also requires the use of a wrench or other tool to unscrew the bolt to free the mold from the concrete after it has set; all of which involves considerable waste of time and labor.
A so-called dowel (screw-anchor), somewhat resembling the general appearance of the present insert, is disclosed in U.S. Pat. No. 809,177, but is designed to be permanently mounted in a preformed hole in a wall with its outer end flush with the surface of the wall.
Another prior insert (U.S. Pat. No. 1,114,013) includes a pin that has a head that is driven into an undersized opening in a mold board. Anchor means is attached to the inner end of the pin. This arrangement has the disadvantage that, after casting, a tool is required to remove the pin from the anchor means and from the mold board.
Another prior insert (U.S. Pat. No. 1,474,956) comprises a mounting plug that is fastened to the inner wall of a mold, and an insert that partially telescopes the plug and is fastened to the plug. In such situation, the mold must be disassembled or collapsed to remove the plug from the insert before the mold can be freed from the casting.
A further prior art insert (U.S. Pat. No. 3,685,783) embodies a frangible portion disposed between two threaded sections of a so-called dowel. One of the threaded sections is screwed into an anchor member and the other threaded section is screwed into a threaded opening in a mold. This requires the use of a tool for mounting the dowel in the anchor member and also to mount the dowel in the mold. A tool must be used to remove the portion of the insert remaining in the mold face after the frangible portion has been broken. A tool is also required to remove the threaded portion of the dowel remaining in the anchor means before anything can be fastened to the anchor member.
When the fact is considered that various concrete structures, building walls, etc., require a substantial number of bolt-anchoring inserts to be embedded therein, an enormous amount of time and labor is wasted in mounting the inserts in a mold and in subsequently freeing and removing the molds after the concrete sets.